When I first power the UNO, the LED at D13 starts flashing a sequence before it runs the sketch (like the classic blink sketch) I have not seen this on the genuine UNO so I am wondering if it's telling me something.
The clone uses CH340G USB to serial chip because other chips (FTDI and AVR) are hard to hand solder. 16u2 for example, the commonly used chip package is not meant to be hand soldered, modifying the design to use larger TQFP would require rearranging a lot of parts. Using FTDI chip is also hard, with pin spacing at .025" while CH340G is .05 and slightly easier for me. (that said, anyone willing to donate me a reflow oven? So I could build smaller parts?)
On power on, it flashes I think 6 times, goes off, flashes 4 times, goes off, flashes 4 times, goes off, flashes 4 times, goes off, flashes 4 times, goes off, flashes 4 times, goes off, then run whatever uploaded code.
I used regular UNO bootloader when I programmed the chip for the new UNO clones I made.